16. Stamp duty is not chargeable under this Schedule on renounceable letters of allotment, letters of rights or other similar instruments where the rights under the letter or other instrument are renounceable not later than six months after its issue.

Instruments relating to non-sterling stock

17. - (1) Stamp duty is not chargeable under this Schedule on the issue of an instrument which relates to stock expressed-

(a) in a currency other than sterling, or

(b) in units of account defined by reference to more than one currency (whether or not including sterling),

or on the transfer of the stock constituted by or transferable by means of any such instrument.

(2) Where the stock to which the instrument relates consists of a loan for the repayment of which there is an option between sterling and one or more other currencies, sub-paragraph (1) applies if the option is exercisable only by the holder of the stock and does not apply in any other case.

18. Where the capital stock of a company is not expressed in terms of any currency, it shall be treated for the purposes of paragraph 17 as expressed in the currency of the territory under the law of which the company is formed or established.

19. - (1) A unit under a unit trust scheme or a share in a foreign mutual fund shall be treated for the purposes of paragraph 17 as capital stock of a company formed or established in the territory by the law of which the scheme or fund is governed.

(2) A "foreign mutual fund" means a fund administered under arrangements governed by the law of a territory outside the United Kingdom under which subscribers to the fund are entitled to participate in, or receive payments by reference to, profits or income arising to the fund from the acquisition, holding, management or disposal of investments.

(3) In relation to a foreign mutual fund "share" means the right of a subscriber, or of another in his right, to participate in or receive payments by reference to profits or income so arising.

Variation of original terms or conditions

20. Where a bearer instrument issued by or on behalf of a non-UK company in respect of a loan expressed in sterling-

(a) has been stamped ad valorem, or

(b) has been stamped with duty under paragraph 6 above (fixed duty on instrument given in substitution for another instrument stamped ad valorem), or

(c) has been stamped with the denoting stamp referred to in paragraph 21(2)(b) below,

duty is not chargeable under this Schedule by reason only that the instrument is amended on its face pursuant to an agreement for the variation of any of its original terms or conditions.